THE NON-INVASIVE VIBRATING ION-SELECTIVE PROBES WILL ALLOW THE STUDY OF TOXINS DIRECTED AGAINST CELLULAR HOMEOSTASIS AND THE MECHANISMS BEHIND ~STEADY-STATE~ ION FLUX. NOT ONLY DO WE EXPECT THIS TO BE USEFUL IN THE ANALYSIS OF TOXIN ACTION BUT WE ALSO EXPECT TO ISOLATE COMPOUNDS OF USE TO THE BIOMEDICAL COMMUNITY. MANY OF THE COMPOUNDS USED IN MODERN NEUROBIOLOGY AND CELL BIOLOGY TO STUDY ION MOVEMENTS, SIGNAL TRANSDUCTION, SECRETION AND OTHERS, ARE ISOLATED FROM LIVING MATERIAL. DR. SHIMIZU~S LAB HAS A LONG HISTORY OF ISOLATING NATURAL PRODUCTS FROM THE MARINE ENVIRONMENT WHICH ACT ON CELL PHYSIOLOGY AND REPLICATION. HIS COMPOUNDS ARE ROUTINELY SCREENED FOR THEIR ANTI-CANCER ACTION. IN ADDITION SHIMIZU HAS AN INTEREST IN UNDERSTANDING THE PHYSIOLOGICAL MECHANISMS UNDERLYING SUCH ACTIONS. TO FACILITATE THIS HE HAS BEGUN WHAT WE FORESEE AS A LONG-TERM COLLABORATION WITH THE NVPF. DR. SHIMIZU HOLDS AN NIH MERIT AWARD.